Process of exotrophy in fish. Effect of heavy metals—Zn and Cu

The review summarizes for the first time the information on effects of Zn and Cu on various links of the fish exotrophy process. It has been shown that essential metals, like the nonessential ones, can produce negative effects on various aspects of the food-procuring behavior, on sensor systems providing alimentary behavior, and on the digestive enzymes realizing digestion in fish of different ecological groups. A particular attention is paid to their different effects on proteinases functioning in stomach and intestine of various fish species as well as on hydrolase activities in their potential nutrition objects (fish and invertebrate animals). Several mechanisms are considered which allow decreasing the negative action of Zn and Cu on the process of fish exotrophy.     

Lake–peat bog transformation recorded in the sediments of the Stare Biele mire (Northeastern Poland)

The history of Stare Biele paleolake (northeast Poland) has been reconstructed using subfossil Cladocera remains and pollen and spores of aquatic and mire plants from a sediment core. Sediment accumulation began approximately 12,000 years ago during the Older Dryas chronozone. Throughout the entire Late Glacial period, the basin was a small, low-trophic state lake with a developed open-water zone. A well-recorded increase in the trophic state started at the beginning of Holocene. The lake reached its highest trophic level during the early and middle Atlantic chronozone. The first human activity in the lake catchment area occurred at this time, as recorded by fern spores and numerous charcoal grains. Repeated rises in lake water level are documented at the beginning and throughout the early part of the Younger Dryas. Two clear events of decreasing lake water levels are recorded, first during the middle part of the Younger Dryas and second in the Preboreal. Terrestrialization processes first intensified at the end of Atlantic period, which appears to correspond to a decrease in pH. Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water     

The Bainbridgia — Dualipora association (Cnidaria,Tabulata): palaeogeographical and palaeoecological implications

The genera Bainbridgia and Dualipora (Cnidaria, Tabulata) have been found together in 4 localities of Early Devonian age (Missouri, USA; Tafilalt, Morocco; Barrandian, Czechoslovakia; Hörre, Germany). Several isolated occurrences of each are also reported. The palaeogeographical and palaeoecological implications of this association are discussed.     

Effects of recent increases in salinity and nutrient concentrations on the microbialite community of Lake Clifton (Western Australia): are the thrombolites at risk?

There has been a strong research focus on optical properties in temperate estuaries but very much less in tropical estuaries. These properties comprise light and beam attenuation dominated by suspended particulate matter, Chl a, and CDOM. Spatially and temporally distributed data on optical properties in a tropical wet and dry estuary are compared and discussed in relation to those of temperate estuaries. Sampling in the Nha Phu estuary, Vietnam, consisted of five stations on a transect from head to mouth that was sampled four times during dry conditions and three times during wet conditions between May 2006 and April 2008. Methods comprised CTD, optical measurements, and water sampling for suspended matter, Chl a, and CDOM. Results showed high light attenuation—K _d(PAR)—in wet conditions and low in dry. K _d(PAR) was highest at the estuary head and lower in the outer part. Spatial and temporal variations in K _d(PAR) were in general dominated by variations in suspended particulate matter concentrations in both wet and dry conditions. Chl a concentrations were low and showed no strong variations between wet and dry conditions. CDOM absorption coefficients were higher in wet conditions with high values at the head and lower in the central part of the estuary. The depth of the photic zone was reduced by up to 50% during wet conditions. A residence time in the estuary of 5–6 days was derived from the rate of change of K _d(PAR) after a period of heavy rain and discharge of freshwater into the estuary. This complied with a residence time of four and a half days derived from a basic physical relation. Optical properties were in general comparable to temperate estuaries in dry conditions although Chl a concentrations were lower in Nha Phu. A second distinctive point, as compared to temperate estuaries, was the episodic character with days of strong rainfall followed by longer periods of dry weather. All sampling, both wet and dry, was carried out in the dry season which implies a less definitive perception of wet and dry seasons.     

The influence of the diel activity pattern of the larvae of Sericostoma personatum (Kirby & Spence) (Trichoptera) on organic matter distribution in stream-bed sediments — a laboratory study

Diel patterns in mobility and feeding behaviour of the larvae of the stream-dwelling trichopteran Sericostoma personatum larvae were investigated. Larvae fed at night on coarse particulate organic matter (CPOM) at the sediment surface. In the daytime they rested a few cm below the sediment surface, during which time their defaecation activity effected a release of fine particulate organic matter (FPOM) into the sediment. The amount of faeces (mean particle size = 0.1 ± 0.044 mm, x ± SD, n = 500) introduced into the sediment by the larvae, evaluated in two experiments, was 0.4–0.56 mg day^–1. This amount did not differ significantly from the organic input resulting from bacterial activity (0.36–0.64 mg day^–1). The presence of S. personatum larvae increased the sediment organic content by 42.9 mg (75.8 %) and 59.8 mg (185.6%) AFDW per 16 cm³ sediment over a 90-day period, as compared with control systems containing no larvae.     

pH-dependence of the specific binding of Cu(II) and Zn(II) ions to the amyloid-β peptide

Metal ions like Cu(II) and Zn(II) are accumulated in Alzheimer's disease amyloid plaques. The amyloid-β (Aβ) peptide involved in the disease interacts with these metal ions at neutral pH via ligands provided by the N-terminal histidines and the N-terminus. The present study uses high-resolution NMR spectroscopy to monitor the residue-specific interactions of Cu(II) and Zn(II) with (15)N- and (13)C,(15)N-labeled Aβ(1-40) peptides at varying pH levels. At pH 7.4 both ions bind to the specific ligands, competing with one another. At pH 5.5 Cu(II) retains its specific histidine ligands, while Zn(II) seems to lack residue-specific interactions. The low pH mimics acidosis which is linked to inflammatory processes in vivo. The results suggest that the cell toxic effects of redox active Cu(II) binding to Aβ may be reversed by the protective activity of non-redox active Zn(II) binding to the same major binding site under non-acidic conditions. Under acidic conditions, the protective effect of Zn(II) may be decreased or changed, since Zn(II) is less able to compete with Cu(II) for the specific binding site on the Aβ peptide under these conditions.     

Declining snake population—why and how: a case study in the Mangrove Swamps of Sundarban, India

Species diversity of reptiles is much higher in Sundarban than in other mangrove ecosystems in India. Presently snakes are declining in Sundarban due to habitat loss caused by tremendous population pressure. Besides, irresponsible killing to avoid snakebite both from poisonous and nonpoisonous varieties is another reason for the gradual declining snake population. According to an intensive household survey in 35 villages in Sundarban, about 22 species (five poisonous and 17 non-poisonous) of snakes have been identified and there appears to have been a general decline in densities. On the contrary, a large number of people are bitten and die from snakebite every year with 0.57 and 0.34 vulnerability and mortality rate per 10,000 people, respectively. The two most commonly observed poisonous species are the common krait, Bungarus caeruleus (51 %) and common cobra, Naja naja (40 %), and that of non-poisonous varieties are the Ptyas mucosus (41 %), Typhlina bramina (34 %), Xenochrophis piscator (12 %), and Amphiesma stolata (10 %). Apart from killing of snakes out of fear; habitat loss, unscientific handling of snakes by snake catchers and charmers, and netting by fisherman contributes to snake mortality to a large extent; 72 % killed snakes are of poisonous varieties, 60 % of which are B. caeruleus, the most venomous snake in Sundarban. This paper is an attempt to highlight some of the important conservation efforts like the introduction of snake firms, alternative employment channels for the snake charmers and catchers, and mass awareness campaign through panchayet (village level governing body) and local NGOs.     

Distribution of micro- (Fe,Zn, Cu,and Mn) and risk (Al,As, Cr,Ni, Pb,and Cd) elements in the organs of Rumex alpinus L. in the Alps and Krkonoše Mountains

Plant and Soil - Rumex alpinus is a native plant in the mountains of Europe whose distribution has partly been affected by its utilization as a vegetable and medicinal herb. The distribution of...     

Paradox and promise: Research on the role of recent advances in paleodemography and paleoepidemiology to the study of “health” in Precolumbian societies

Bioarcheology has made tremendous strides since the subdiscipline's inception, subsequent syntheses, the standardization of data collection methods, and analytical advances ranging from molecular analyses through age-estimation and biodistance. Concurrently, health and the adaptive success of past populations have remained primary concerns. However, questions are routinely raised about lesions and whether or not changing frequencies are synonymous with increases or decreases in stress, morbidity, and overall health. These include how and why healed lesions can simultaneously represent stress and survival, demanding that researchers understand how population dynamics influence skeletal sample formation. In this study, methods to analyze age- and sex-specific mortality patterns prior to, and in conjunction with, the analysis of linear enamel hypoplasias are demonstrated. Paleodemographic and paleoepidemiological models are presented for late Pre-Columbian skeletal samples from the Eastern Woodlands. Results of hazard modeling demonstrate that elevated mortality rates were commonplace during the latter half of the Mississippian period (AD 1200–1450) with reproductive-age females experiencing high age-specific risk of death attributed to the development of fortified villages and novel environments for increased pathogen loads. Corollary results are presented for the age-specificity of linear enamel hypoplasias in the central Illinois River valley. The epidemiological models demonstrate that the relationship between adult mortality and early childhood stress varied through space, culture, and time. These findings highlight the need to effectively operationalize measurements related to health and stress in past populations and support the adoption of selective mortality and heterogeneity in frailty as key concepts in bioarcheological research. Am J Phys Anthropol 155:268–280, 2014. © 2014 Wiley Periodicals, Inc.     

Fast and slow photoreceptors — a comparative study of the functional diversity of coding and conductances in the Diptera

1. From a comparison of the photoresponses and membrane properties of photoreceptors from 20 species of Diptera, we conclude that coding in the time domain is matched to the dictates of visual ecology. This matching involves the dynamics of phototransduction and the use of an appropriate mix of potassium conductances to tune the photoreceptor membrane.
2. Rapidly flying, manoeuvrable diurnal Diptera from several families have fast photoreceptors, with corner frequencies (the frequency at which signal power falls by a half) of between 50 and 107 Hz. The ponderous and predominantly nocturnal tipulids have slow photoreceptors with fully light adapted corner frequencies of 16 to 19 Hz.
3. Dark adapted fast photoreceptors have a lower gain (as indicated by lower noise levels), a lower sensitivity, and light adapt more rapidly than dark adapted slow photoreceptors. Fast cells also have much lower input resistances and shorter time constants.
4. Fast photoreceptors rectify more strongly in the steady state because of a weakly inactivating delayed rectifier potassium conductance with fast and slow components of activation. Slow photoreceptors rectify less strongly in the steady state because their membrane properties are dominated by strongly inactivating outward currents with reversal potentials in the range — 80 to -90 mV.
5. The differences between potassium conductances match the differing functional requirements of fast and slow photoreceptors. The non-inactivating delayed rectifier promotes the rapid response of fast cells by reducing the membrane time constant. This is an expensive strategy, involving large conductances and currents. Slowly flying nocturnal insects do not require a high speed of response. The potassium conductances in their slow photoreceptors inactivate to avoid costly and unnecessary ion fluxes.
6. Both the dynamics of the photoresponse and photoreceptor membrane properties exhibit sexual dimorphism. Light adapted photoreceptors in the enlarged male dorsal eye of Bibio markii have a corner frequency of 42 Hz, compared with 27 Hz for cells in the smaller female eye. This difference in frequency response correlates with the male's higher spatial acuity and is accompanied by consistent differences in potassium conductance activation rate. We conclude that the divison between fast and slow cells is the product of cellular constraints, metabolic costs and the requirements of coding efficiency at different light levels and retinal image velocities.

     

Evaluation of the allergenicity of ω5-gliadin-deficient Hokushin wheat (1BS-18) in a wheat allergy rat model

We previously developed Hokushin wheat line as a hypoallergenic wheat lacking ω5-gliadin (1BS-18), a major allergen for wheat-dependent exercise-induced anaphylaxis. However, the allergenicity of 1BS-18 has not been understood completely. In this study, we evaluated the allergenicity of 1BS-18 such as anaphylactic elicitation ability and sensitization ability using rats sensitized with ω5-gliadin or glutens prepared from Hokushin (Hokushin gluten) or 1BS-18 (1BS-18 gluten). Rats were sensitized by intraperitoneal administration of ω5-gliadin, Hokushin gluten or 1BS-18 gluten. Immunoglobulin E-mediated systemic anaphylaxis was evaluated by measuring changes in rectal temperature for 30 min after intravenous challenge with ω5-gliadin or the test glutens in unsensitized rats or rats sensitized with ω5-gliadin or the test glutens. In ω5-gliadin-sensitized rats, intravenous challenge with ω5-gliadin or Hokushin gluten significantly decreased the rectal temperature at 30 min after challenge while challenge with 1BS-18 gluten did not reduce the rectal temperature. Furthermore, intravenous challenge with ω5-gliadin significantly decreased the rectal temperature in rats sensitized with Hokushin gluten or 1BS-18 gluten. However, the reduced degree observed in 1BS-18 gluten-sensitized rats was smaller than that in Hokushin gluten-sensitized rats. In conclusion, 1BS-18 elicited no allergic reaction in ω5-gliadin-sensitized rats and had less sensitization ability for ω5-gliadin than that of Hokushin wheat.     

Earthworms as bioindicator of metals (Zn,Fe, Mn,Cu, Pb and Cd) in soils: Is metal bioaccumulation affected by their ecological category?

The importance of earthworms in metal pollution monitoring is widely recognized in terrestrial ecosystems. Metal bioaccumulation by soil-dwelling earthworms can be used as an ecological indicator of metal availability in soils. In this study, we quantify the level of DTPA extractable metals in casts and tissues of earthworms (endogeic: Metaphire posthuma (Vaillant) and anecic: Lampito mauritii Kinberg) and ingesting soils, collected form cultivated land, urban garden and sewage soils. Soil and worm casts collected from sewage and cultivated land showed the greater metal concentrations. The concentration of Zn, Fe, Pb and Mn in earthworm casts was in the order: sewage soil > cultivated land > urban garden, while for Cu and Cd the order was cultivated land > sewage soil > urban garden. Data suggested that the level of DTPA extractable metals was higher than that of surrounding soils. We got close relationships between metal concentration in worm tissues and surrounding soils: Zn (r² = 0.94 and 0.89, P < 0.01 for both), Fe (r² = 0.95 and 0.97, P < 0.01 for both), Cu (r² = 0.93 and 0.96, P < 0.01), Pb (0.63, P < 0.01 and 0.57, P > 0.05), and Cd (r² = 0.15, P > 0.01 and 0.75, P < 0.01), respectively, for M. posthuma and L. mauritii. The study clearly indicates that earthworms have efficient potentials for bioaccumulation of metals in their tissues which can be used as an ecological indicator of soil contaminations. A species-specific metal accumulation pattern was observed in studied earthworms. Comparatively, endogeic showed the higher metal contents in their tissues than anecic (t-test: P < 0.05); collected form different habitats studied. Data suggested that species-specific feeding behaviour, earthworm niche structure, ecological category of inhabiting earthworm and even horizontal distribution of contaminants in soil layers are some major determinant for metal accumulation patterns in soil dwelling earthworms. The difference in burrowing patterns can influence the patterns of metal bioaccumulations between endogeic and anecic, although other factors are also contributory. Further more detailed study is still required to elaborate the proposed hypothesis.     

Case study on the efficacy of a lanthanum-enriched clay (Phoslock®) in controlling eutrophication in Lake Het Groene Eiland (The Netherlands)

Lake Het Groene Eiland was created in the beginning of 2008 by construction of dikes for isolating it from the surrounding 220-ha water body. This so-called claustrum of 5 ha was treated using lanthanum-modified clay (Phoslock^®) to control eutrophication and mitigate cyanobacterial nuisance. Cyanobacteria chlorophyll-a were significantly lower in the claustrum than those in the reference water body, where a massive bloom developed in summer, 2008. However, PO₄-P and TP did not statistically differ in these two waters. TN and NO₃-N were significantly lower in the claustrum, where dense submerged macrophytes beds developed. Lanthanum concentrations were elevated after the applications of the modified clay in the claustrum, but filterable lanthanum dropped rapidly below the Dutch standard of 10.1 μg l^?1. During winter, dozens of Canada geese resided at the claustrum. Geese droppings contained an average of 2 mg PO₄-P g^?1 dry weight and 12 mg NH₃-N g^?1 dry weight and might present a growing source of nutrients to the water. Constructing the claustrum enabled unrestricted bathing in subsequent three summers, as no swimming bans had to be issued due to cyanobacteria blooms. However, the role of the modified clay in this positive outcome remains unclear, and longevity of the measures questionable.     

A quantitative ultrastructural study of Chromatium minus in the bacterial layer of Lake Cisó (Spain)

A quantitative ultrastructural study was performed with samples taken throughout a layer of the purple sulfur bacterium Chromatium minus in Lake Cisó (Spain). Ultrathin sections of cells were analyzed by transmission electron microscopy, in order to study the size, number and volume of intracytoplasmic membranes (ICM), sulfur globules and poly--hydroxybutyrate (PHB) granules per unit volume of cell. Important differences were seen between cells from the top (receiving 60 E · m^–2 · s^–1 at noon) on the one hand, and cells from the peak and bottom parts of the bacterial layer (receiving less than 1 E · m^–2 · s^–1) on the other hand. The amount of ICM per cell increased as a function of depth being about three times higher in bottom cells than in top cells. Neither statistically significant differences in cell size, nor in numbers of sulfur globules were found, but the ultrastructure changed with depth. Finally, the most important changes throughout depth were detected in PHB granules. Top cells had 0.5% of their volume occupied by PHB granules, whereas in the bottom cells the corresponding value was 12.2%. These changes were due to the number of PHB granules per unit volume of cell since globule size was constant.Non-common abbreviations ECM intracytoplasmic membrane systems - PHB poly--hydroxybutyrate - Bchl bacteriochlorophyll - SED sphere equivalent diameter     

Assay of α-amylase in soil and river sediments: Its use to determine the effects of heavy metals on starch degradation

α-Amylase (1,4-α-d-glucan glucanohydrolase EC 3.2.1.1) activity was assayed and characterized in soil and in starch amended river sediment. Zero order reactions between initial activity; length of incubation; soil or sediment weight; and substrate concentration were demonstrated. Optimum pH for α-amylase activity in soil was 5.0 and in sediment 5.9–6.2, while the temperature optima were 37°C and 45°C respectively. The addition of starch to samples of sediment led to a marked increase in α-amylase and numbers of amylolytic bacteria. An example is also given of how the assay can be used to determine the effects of heavy metals on α-amylase activity in a river sediment.     

Eutrophication and recovery of Lake Vesijärvi (south Finland): Diatom frustules in varved sediments over a 30-year period

Lake Vesijärvi was loaded by sewage from the City of Lahti for 60 years until 1976 when the discharge was diverted. Paleolimnological analyses of the varved bottom sediment indicate that the sedimentation rate within the Enonselka basin, the most eutrophic part of the lake, has been as high as 2 cm yr^–1, and total phosphorus accumulation was 20–40 g P m^–2 yr^–1, during the last 20 years. Within the less eutrophic Laitialanselkä basin, the sedimentation rate did not exceed 1 cm yr^–1, and the formation of varved sediment only began at the end of the 1960's, i.e. about 10 years later than in Enonselkä.Planktonic diatom production was highest in the Enonselka basin. The most abundant diatoms in the sediment between 1970–1985 were Asterionella formosa, Aulacoseira islandica and Stephanodiscus spp. Fragilaria crotonensis and Tabellaria fenestrata had low abundances in the middle of the 1970's but increased again at the end of the 1970's. Asterionella formosa and Diatoma elongatum reached their maxima between 1979–1984 when the hypolimnion of the Enonselk/:a basin was aerated artificially. In the Laitialanselkä basin, the production of planktonic diatoms has been lower and the species composition of the diatom community differed from that in Enonselkä. However, at the end of 1980's the total accumulation of diatoms in Laitialanselkä approached levels which were observed at the end of 1950's in Enonselkä, prior to the rapid eutrophication period.The production and thereby the sedimentation of diatoms has decreased towards the end of the 1980's in Enonselkä, indicating reduced nutrient availability in the lake water. This reduction was due to the decreased external loading of phosphorus as well as to the decreased release of phosphorus from the sediment as a result of improved oxygen balance in the hypolimnion.     

Impact of malathion on acetylcholinesterase in the tissues of the fishTilapia mossambica (Peters)—a time course study

The sublethal toxic potency of malathion in inhibiting acetylcholinesterase activity of brain, muscle, gill and liver tissues of the fish,Tilapia mossambica was studied at 12 h intervals. Maximum in hibition at 36 and 48 h, and complete revival of acetylcholinesterase activity after 72 h was noticed, suggestive of the loss of inhibition of the enzyme activity was probably by suitable (acetylcholine) accumulation.